Precast masonry stairs



- 1957 T. H. PRICE PRECAST MASONRY sums Filed Sept. 7, 1954 A wmm INVENTOR; THOMAS H. PIP/0E BY a ATTORNEY 1 I II! llnited States Patent PRECAST MASQNRY STAIRS Thomas H. Price, San Mateo, Calif., assignor to National Tile & Terrazzo Company, San Francisco, Calif, a corporation of California Application September 7, 1954, Serial No. 454,346

2 Claims. (CI. 72-96) This invention relates to precast masonry stairstep construction for buildings and more particularly relates to such step construction in which leakage of water is eliminated between next adjoining step units.

Heretofore there has been present in such a precast masonry stair steps a problem of preventing leakage of water through the joints at the angle formed between the planar face of one tread and the riser member which extends from the tread to the step next above. In such angle formed by a tread and a riser in the present known precast masonry stairs, the riser has been a part of the precast assembly by being cast as a depending member from the forward edge of the step tread next above and its free edge has extended to the rear edge of the tread next below with a strip of mortar spread between the said lower free edge of the riser and the face of the subjoined tread. The tread and riser are reinforced at their rear face by an integral concrete base slab which conforms to the connecting angle of the tread and the depending riser. The riser and tread are, therefore, at the outer face of the angle of the concrete reinforcing base slab. This prior construction has resulted in numerous difii-culties, firstly, the unsupported strip of mortar at the angle between a riser and the step tread next below will shrink a trifle when it sets since there is no reinforced integral concrete base to support it; secondly, water settles and remains most persistently in the inside angle between the tread and the riser and gradually disintegrates the unsupported cement in the angle; thirdly, if there is any settling of the steps a crack will occur at this inside unsupported angle; fourthly, when such a crackoccurs the weight of the riser will be depending from the next above tread and not supported at its base, which thereby causes it to drop or sag. From these causes and probably others, a crack will form in the angle at the rear of the tread and cause leakage of water therethrough as well as disintegration of the mortar strip between the tread and riser.

The purpose of the present invention is to eliminate such leakage between such prefabricated steps units and support the riser from its base so that it will not sag and cause an unsightly appearance at this promiently visible portion of the completed stairway. Briefly described, the invention consists of precast or prefabricated step units adapted for suitable support at the opposite ends by inclined precast, reinforced stringers, the prefabricated step units having an integral reinforced concrete base slab comprising a tread support and a riser support formed at substantially 90 degrees, the tread support having a tread member extending from the angle to beyond the next-below riser and terminating in an overhang at the free end of the tread support, and a riser adhering to the vertical back portion of the concrete base support and extending from adjacent said angle substantially to the upper edge of the back or riser support so as to fit within the overhang of the tread of the next above step tread to underlie the overhanging portion thereof. Thus the relatively adjacent edges of tread and riser and the mortar joint therebetween are inside of the angle of the integral reinforcing base. Such precast or prefabricated strip units are supported at each of their opposite a 2,815,657 Patented Dec. 10, 1957 ICC ends on an inclined precast reinforced concrete stringer upon which rests the integrally formed angle of the concrete base, the precast step being securely positioned on the stringer by a body of mortar or other suitable cementitious aggregate.

Preferred forms in which the invention may be exemplified are described herein and illustrated in the accompanying drawing, in which:

Fig. 1 is a perspective view of one form of a precast step of the invention.

Fig. 2 is an enlarged vertical lateral transverse section on line 2-2 of Fig. 1.

Fig. 3 is an end view of a stairway employing the precast steps of Figs. 1 and 2 supported on a precast stringer member.

Fig. 4 is a perspective view of a modified form of a precast step of the invention.

Fig. 5 is an enlarged vertical lateral transverse sectional view on line 55 of Fig. 4.

Referring to the drawing in which like reference characters indicate corresponding parts in the several views, and referring firstly to the exemplified form shown in Figs. 1, 2 and 3, a suitable upright support is provided which may be a structural part of a building, but for purposes of example is indicated herein as a precast concrete post 10 suitably reinforced by wire webbing 11. The post obviously rests upon a suitable base and at its upper end supports in the usual manner the elevated end of an inclined precast concrete stringer 12 which also is preferably reinforced by wire webbing 13, the opposite end of the stringer being based upon the ground or any other suitable foundation which may be available for the flight or series of steps forming the stairs. It is to be understood that there are two such supports such as post 10, and two such stringers 12, a post and corresponding stringer being relatively spaced at each of the opposite ends of the flight of steps, and if desired, additional supports and stringers may be employed intermediate said opposite ends in the event that the stair is of such width as to require such additional reinforcement.

Extending between the pair of stringers are precast masonry step members generally indicated 14. In Figs. 1 and 2 the step members comprise a concrete integral base having a horizontal tread slab 15 and a vertical riser slab 16 forming therebetween an inside angle indicated 17, the base being reinforced longitudinally, and laterally and around said angle, by-heavy wire strands or relatively light bars 18 which are embedded by precasting in said base and preferably are relatively spot welded at intersections as at 18a providing an integrated mesh. As shown in Figs. 1 and 2, for certain types of tread facing material, the horizontal base slab 15 may be inclined from the inside angle 17 to its free end, as at 19.

There is mounted by cementitious bond on the horizontal obverse face of the base slab 15 a row consisting of a plurality of side by side tread facing members 2i) having lower faces opposed to and superficially cast and cementitiously bonded on the horizontal base slab 15, the tread face members being shaped at such lower face to conform to the planar face of the base slab if the latter be inclined as in Figs. 1 and 2, or stated conversely, the poured concrete slab conforms to the shape of the lower face of the tread facing members. The tread facing members extend forwardly beyond the free end of the horizontal tread base slab 15 providing a tread overhang portion 22 at the forward free end of the tread.

The vertical riser base slab 16 has a row of side-byside riser facing members 23 flushly recessed into and cementitiously bonded superficially integral with the front or obverse face thereof, the lower edge of the riser face members being spaced from the inside angle 17 of the base slab and is also spaced from the plane of the exposed upper face of the tread facing member by a strip of mortar 24, the upper edge of the riser face members preferably terminating in register with the upper free edge of the riser base slab as at 25.

The facing members 20, 23 for the respective treads and risers in a completed step structure are preferably relatively spaced in side-by-side series in each step. In a step of the character described there are a plurality of the facing members which are described as bricks 20, and risers 23 in Figs. 1 and 2.

In adapting the separate precast steps to use in a stairway, the outside angle 26 formed by the intersection of the rear or reverse faces of the precast base slab is supported upon the relatively spaced inclined stringers 12 and suitable supporting material such as brick, cement aggregate 27, or both combined, may be filled in as support between each of the reinforced base slabs and the stringer. The coterminus upper free ends of the riser face members 23 and the riser base slab 16 underlie the overhanging portion 22 of the tread of the next above step, and are secured in position by a tier of manually applied mortar 28 which, due to the overhang portion 22 at the front of the tread, is not appreciably visible from the front of the completed stairs.

In Figs. 1 and 2 the tread facing members 20 are of the usual clay brick material having tread faces elongated rectangularly, and the exposed sight or view face 20a substantially square at the exposed end, the bottom face thereof being preferably inclined in a uniform plane toward the tread face at the opposite end, as at 29, and thus provides for a substantially greater thickness of the underlying base slab at the angle than at its forward end where the tread may be supported upon the underlying riser of the step next below.

In the exemplified forms of the invention, it will be noted that the inner end of the tread facing member 20 fits snugly into the inner angle 17, and does not enter under the vertical riser slab 16, and that the riser facing member 23 is inset into the front face portion of the riser slab 16 so that its front face is in the vertical plane of said angle, the upper end of the riser facing terminating in register with the upper end of the slab and having its lower end spaced from said inner angle a greater distance than the thickness of the tread facing member. Such structure and spacing provides a maximum of thickness and strength to the base slab member at the angle, provides a solid cement backing for the adjacently spaced ends of the facing members, and provides for the finishing mortar strip 24, and also eliminates possibility of water leaking into any crevice between said spacing members and the base slab at such inside angle.

While in the foregoing description the step and the stair have been described in the manner of building a stair from the base up, the separate step members are constructed and precast in an inverse order of first laying the tread facing members 20 and riser facing members 23 in a molding form, said facing members being properly spaced relatively by intervening strips which are later removed, but which provide indented strip spaces for placing cementitious mortar 21a and 24 in the spaces between the facing members after removal from the molding form. Since the finally exposed faces of the tread and riser members are in contact with the molding form the rear faces are exposed, whereupon the reinforcing material 18 is suitably positioned and the concrete base slabs 15, 16 poured at the rear face of the mortared facing members to enclose the reinforcing wires or bars 18 and thus provide an integrated precast masonry step member having the visible tread and riser at the inside face of the angle of the base slab, whereby there is no joint at the angle when the steps are formed into a stair with the riser extending upwardly from the tread .to underlie the overhang of the forward edge portion of the tread of thestep next above.

In the modification of Eigs. 4 and 5 the manner of forming the step and stairs is the same as set forth in the next preceding paragraph. In this modification of Figs. 4 and 5 the integral cast cementitious face slab is generally indicated 30 consisting of relatively perpendicular vertical riser portion 31 and horizontal tread portion 32, providing therebetween an inside angle 33 and an outside angle 34, the base slab being reinforced similarly as in Figs. 1 and 2 by rods or wires 18, 18a. In this modification the horizontal tread portion 32 of the base slab is of uniform thickness and the tread face member 35 is preferably of fabricated tile of substantially uniform thickness throughout the area of the tread and which extends beyond the free terminal edge of the horizontal base slab, thereby providing an overhang portion 36 at the free or forward edge of which there is a downturned or depending lip 37, the riser portion 31 of the next-below step entering under said overhanging portion 36 of the tread member and the tier of mortar 28 in the joint therebetween being concealed from view by the depending lip. Riser face members 38 of tile are employed in this modification in similar manner as the riser face members 23 of Figs. 1 and 2, and mortar strips 21a and 24 are similarly employed between said tile.

Having thus described the invention, What is claimed as new and patentable is:

1. A stair step structure for building construction which has relatively spaced upwardly inclined supports for supporting a step structure therebetween, said step structure having a precast cementitious integral base consisting of a tread slab and a riser slab relatively angularly disposed providing an obverse face having an inner angle and a reverse face having an outer angle, a plurality of side-'by-side relatively spaced tread face members and riser face members bonded cementitiously superficially integral with the respective inner angle faces of said tread and riser base slabs, and a cementitious filler at the visible face of the step structure in the spaces between the said face members, said tread face members having one end thereof set snugly into said inner angle of the base slab and the opposite end extending beyond the free edge of the tread base slab providing an overhanging portion beyond the adjacent end of the tread base slab for receiving thereunder the upper end of a riser of a step member which is next below in a series of steps, and said riser face members being inset into the face portion of the riser slab whereby the front faces of the riser face members are in the vertical plane of said inside angle, said riser face members having their upper ends coterminous with the upper edge of the riser slab and their opposite lower edge spaced from said inner angle a greater distance than the thickness of the tread face member at said angle, whereby said lower edge of the riser face member is supported upon the integral base member in spaced relation to said inner angle and the integral base may have maximum thickness at its angle, the relatively adjacent edges of the tread and riser face members abutting said integral base in relatively spaced relation adjacent to said inner angle.

2. A stair step structure for building construction having the elements of claim 1 and in which the end of the tread face members are of greater thickness at the outer free end than at the inner end adjacent said inner angle and providing an inclined plane at the bottom face of the tread face members, the opposing face of the tread base slab being correspondingly inclined.

References Cited in the file of this patent UNITED STATES PATENTS 1,497,058 Barriball June 10, 1924 2,577,864 Thornton etal Dec. 1], 1951 FOREIGN PATENTS 255,991 Germany of 1913 137,466 Australia .of 1934 8. ra e 0 19.37 

